C3 LS4 Intake restoration

[Tom K.]

Hello All,

Im back again looking for advice on re-assembling my intake manifold.
My goal is to install something that would not have to be redone later by another owner if he or she wants to have the car judged. The car is a 1973 Coupe with a 454, Automatic trans, A/C, PB, PS, PW. I have been looking though the JG and I dont see much info on the finishes on some of the parts. In the pix below you will see what I have so far.
I dont know what I should do with the hose fittings for the heater hoses, the bolt and lock washer for the EGR hold down and the stamped cover for the thermostatic choke spring. My understanding from one of other guys is that the EGR hold down bracket may have been finished in black oxide. Is this correct? I can get the black oxide finish, but what do you typically do to prevent corrosion? The black oxide will provide some rust protection, but not much.

Also, from the JG, I think the thermostat housing is supposed to be 3972128, not the one (3877660) shown in the picture. The caption below the picture on pg 159 is incorrect I think.

Any constructive criticism is welcome and appreciated.

Thanks for your help as always


Tom

[Mark E.]

Re: C3 LS3 Intake restoration

Looking nice Tom! Originally, the intake, thermostat housing and their bolts were painted with the engine as an assembly. Which means the edges of the intake gasket are painted too. So install these and respray. Same goes for the valve covers.

The distributor clamp is natural, and the EGR bracket has a black finish (phosphate, oxide?). Hose bibs are installed after the the engine is painted.

The Q-Jet finishes and fasteners looks good, but check the color of the return spring (blue?).

BTW this is an LS4.

[Tom R.]

Re: C3 LS3 Intake restoration

Also, from the JG, I think the thermostat housing is supposed to be 3972128, not the one (3877660) shown in the picture. The caption below the picture on pg 159 is incorrect I think.

I believe you're referencing the L48/L82 housing with the 3877660 number . The 3rd edition of the 73/74 TIMJG states:

The LS4 uses thermostat housing 3972128 or 336773

Post a photo of your thermostat...closeup.

[Jimmy P.]

Re: C3 LS3 Intake restoration

Tom,
Here are a few photos from my 73-74 Revision Files. Hope they help with finishes. These are from an original 73 LS4, of an NCRS member. He no longer owns this car.This thermostat is the 128 on this car. I’ve also included a couple photos showing the metal PCV hose metal extension tube and mount. Unique to the LS4.
Yes Mark, the carb return springs on the 73 were a powder blue color.
Hope these help!

PS…Maybe one of the administrators can change the thread title to LS4,!

[Tom K.]

Re: C3 LS3 Intake restoration

I believe you're referencing the L48/L82 housing with the 3877660 number . The 3rd edition of the 73/74 TIMJG states:



Post a photo of your thermostat...closeup.

Hello Tom - I got the 3877660 number from the photo on PG 159 of the 73-4 JG Fig M 18.12 The caption says " Thermostat housing 3877660 with tab for return spring unused on all corvette applications"
I miss-interpreted that (more brain fade on my part) and repainted a housing of that P/N which I got along with a replacement intake manifold (I was able to get the correct P/N and a relevant casting date too!) that I bought online because my original was replaced by a P-O. I found the chart on pg 160 which states all 1973 LS4's used thermostat housing 3972128. Fortunately this housing is still on my car with the incorrect (although factory CI) intake manifold. The P-O removed the original and installed one without EGR and some factory chrome valve covers for a nice factory look but no EGR.
I had sprayed some paint on the original when I replaced the thermostat. The paint is now so thick its really hard to read the p/n but its there.
Pix below. Does anyone need a p/n 3877660 thermostat housing painted nicely? I got a spare

[Tom K.]

Re: C3 LS3 Intake restoration



Jimmy - thank you for those pix!!

They have really good detail on things like the intake manifold bolts. Now I know what is correct on my car and what was changed. From the JG (pg 128 fig M7.8) I got the impression that the bolts were a hex bolt with a thicker washer. In the text they say it is a shouldered bolt. But what is in your pic above is the same as is on my car. I believe it to be correct based on the story from the P-O.
When I painted the spring, I just used a pale blue spray can I had lying around. I thought it looked ok, but does anyone have any info on the correct color?
Lastly, by chance, do you have more pix showing the area around the distributor? The pic in the JG showing the lift hook near the distributor is from the top down (pg 129 fig M 7.13) and as mine is missing, I'm not sure of the shape of that part.
My front lift hook looks correct including fasteners, but no stamping is evident. I have added pix below. Also FWIW there is an overall pic looking down to show the rest of the intake that is currently on the car. If anyone notices anything else, please chime in. I do have the correct fan and clutch and the wiring on the passenger side will be next after the intake.

Again, thank you all for the help!


Tom

[Jimmy P.]

Re: C3 LS3 Intake restoration

Tom,
Here is what I have on the rear 454 lift brackets. The first one is from a 73, and the second one is from a 74. Not sure if the second one isn't the one used in the manual. But this photo is a bit clearer.

[Tom K.]

Re: C3 LS3 Intake restoration

Jimmy,


Thanks for these pix - I will start scrounging around to find the rear lift eye. This forum is an incredible resource!


Tom Krause

[Tom K.]

Re: C3 LS3 Intake restoration

Thanks everyone for your interest. Is there someone who could help with what the correct finishes are for the heater hose fittings and the distributor hold down?

Tom

[Mark E.]

Re: C3 LS3 Intake restoration

Thanks everyone for your interest. Is there someone who could help with what the correct finishes are for the heater hose fittings and the distributor hold down?

Tom

Tom- this is covered in one of the posts above.

[Tom K.]

Re: C3 LS3 Intake restoration

Tom- this is covered in one of the posts above.

Mark,
One of the previous posts does state that the hose bibs are installed after the engine was painted. But I dont know if they were plated or raw. The ones I have are not the best of condition and Im not sure if I should do something with them or not.
The same post says that the distributor hold down down is raw, but I dont know if I have ever seen one that wasnt painted orange. I have played with old chevrolets for a long time, but am no ones expert. Also, when I looked through the JG there were pix on pg 130,131 & 132 that all show orange hold down clamps. The picture on pg 130 that shows the chisel mark (Fig M 8.1) shows the chisel mark just fine. I cannot tell what the hold down looks like or perhaps it was removed to show the chisel mark?
I dont have enough experience doing correct restoration work to know and Im trying to be confident Im on the right track.

Again,
I really appreciate the help from everyone and their expertise.

Tom